Average Follow-up Time DetailThe study period ran from January 1, 1991 through December 31, 1998.

Exposure DetailInterviewers ascertained exposure information by administering interviews at home at each study cycle. Complete information on NSAID and other drug prescriptions was available in automated form during the study period from January 1, 1991, through December 31, 1998 and included the product name and other information (e.g., the international non-proprietary name of the drug, number of tablets, capsules, or other vehicle in the filled prescription, the date of delivery of the product, the prescribed daily number of tablets to be taken, the drug dosage, and the duration of the prescription period). The investigators reported results separately for ever vs. never non-ASA NSAID use, duration of non-ASA NSAID use, non-ASA NSAID dosage, and duration of ASA use. This entry pertains to results on duration of ASA NSAID use.

The investigators compared incident AD risk in four groups: the reference group of participants who did not use ASA NSAIDs at any time ("Non-use"), the group of participants who had at most 1 month of cumulative ASA NSAID use ("Short-term use"), the group of participants who had more than 1 but less than 24 months of cumulative ASA NSAID use ("Intermediate-term use"), and the group of participants who had at least 24 months of cumulative ASA NSAID use ("Long-term use").

Ethnicity DetailThe distribution of ethnicity is not reported. The participants included residents of Ommoord, a suburb of Rotterdam, the Netherlands.

Age DetailThere were 3162 (45.2%) participants who were less than or equal to 65 years old; 2323 (33.2%) participants who were of ages 66-75; and 1504 (21.5) participants who were greater than 75 years old

"Both at baseline examination and follow-up examinations, the subjects were examined for dementia according to a three-step protocol." This included the MMSE, GMS, CAMDEX, neuropsychological examination, and an MRI."

"In addition to undergoing screening for dementia, the subjects were continuously monitored for cases of dementia during followup (33). A clinical diagnosis of dementia was made according to the criteria of the Diagnostic and Statistical Manual of Mental Disorders, third edition, revised, by a panel that reviewed all existing information. A subdiagnosis of Alzheimer’s disease was made according to the criteria of the National Institute of Neurological and Communicative Diseases and Stroke–Alzheimer’s Disease and Related Disorders Association (39). A subdiagnosis of vascular dementia was made according to the criteria of the National Institute of Neurological Disorders and Stroke–Association Internationale pour la Recherche et l’Enseignement en Neurosciences (40)."

"We calculated the relative risks of dementia (and 95 percent confidence intervals) with the use of a Cox proportional-hazards model(41); the cumulative use of each drug was represented by a time-dependent covariate. In the Cox model, age in days was used as the time axis to ensure optimal adjustment for age. (42)"